How to Check Your DHT Levels: Tests and Results

Checking your DHT levels typically involves a simple blood draw, with the sample sent to a lab for analysis. The most reliable method currently available is liquid chromatography-tandem mass spectrometry (LC-MS/MS), though older immunoassay-based tests are still in use and can produce meaningfully different numbers. The choice of lab method, the medications you take, and even the supplements in your medicine cabinet can all shift what the report says, which makes understanding the test almost as important as getting it done.

Why Someone Would Check DHT in the First Place

DHT is a potent androgen produced when the enzyme 5-alpha reductase converts testosterone. It plays a central role in several processes that prompt testing. In men, the most common reasons involve hair loss and prostate issues. Both androgenic alopecia (male-pattern baldness) and benign prostatic hyperplasia (BPH) are driven in part by DHT activity. DHT stimulates prostate growth and can cause the gland to enlarge over time, leading to urinary symptoms that often prompt a workup including hormone levels.¹ Prostate growth and androgenic alopecia share this DHT link, which is why the same class of drugs (5-alpha reductase inhibitors) is used to treat both conditions.²

In women, DHT testing usually comes up during an evaluation for excess body or facial hair growth (hirsutism) or other signs of androgen excess. Hirsutism affects roughly 4 to 11 percent of women in the general population, but the rate jumps to an estimated 65 to 75 percent in women with polycystic ovary syndrome (PCOS), where it is the main outward sign of elevated androgens.³ A doctor investigating PCOS or unexplained virilization may order DHT alongside total and free testosterone to get a fuller picture of androgen activity.

Less commonly, DHT testing is used in the evaluation of children or adolescents with ambiguous genitalia or suspected disorders of sex development. A rare genetic condition, 5-alpha reductase type 2 deficiency, prevents the body from converting testosterone to DHT adequately. More than 50 different mutations of the responsible gene have been identified in affected patients worldwide.⁴ In these cases, the testosterone-to-DHT ratio becomes a key diagnostic clue.

The Standard Test Is a Blood Draw

The most common way to measure DHT is through a venous blood sample, usually drawn from your arm just like any other blood test. Most doctors will ask you to come in during the morning hours, because androgen levels follow a circadian rhythm and tend to be highest early in the day. Fasting is not always required, but your provider may ask you to fast depending on what other hormones are being checked at the same time.

Once drawn, the blood sample is sent to a laboratory that processes it to separate the serum, and then measures the DHT concentration. What matters a great deal here is which analytical method the lab uses, because two widely used techniques can produce very different numbers from the same sample.

Why the Lab Method on Your Report Matters

Older labs may still use radioimmunoassay (RIA) to measure DHT. Newer labs have shifted to liquid chromatography-tandem mass spectrometry, usually abbreviated LC-MS/MS. The difference between these two approaches is not subtle. In head-to-head comparisons, DHT values measured by RIA come back consistently higher than those measured by LC-MS/MS.⁵ One validation study found that the average percent difference between the two methods was about 63 percent, with RIA reading higher. The gap was especially pronounced at lower DHT concentrations, where differences between the methods varied wildly, ranging from about +30 to -140 percent in samples below a certain threshold.⁶

The reason for the discrepancy is that immunoassays are less selective. They can pick up other substances in the blood that resemble DHT closely enough to cross-react with the antibody used in the test. LC-MS/MS physically separates molecules before measuring them, which avoids most of that cross-reactivity. An older technique called Celite chromatography, when added before RIA, reduces the gap somewhat by filtering out some interfering substances, but the LC-MS/MS results still tend to be lower and are generally considered more accurate.⁷

This has a practical consequence you should be aware of. If you get your DHT measured at one lab using RIA and then follow up at a different lab using LC-MS/MS, the numbers may look like your DHT dropped dramatically even if nothing actually changed. Always note which method was used, and try to use the same lab for serial measurements so you are comparing like with like.

Dried Urine Testing

Some providers and direct-to-consumer testing companies offer dried urine tests that measure hormone metabolites, including DHT-related ones, from urine samples collected on filter paper at home. The appeal is convenience: you collect samples at several points during the day, let them dry, and mail them in. Validation studies have shown that reproductive hormone results from dried urine are in excellent agreement with results from traditional liquid urine collection, with very high correlation between the two methods.⁸

That said, dried urine tests measure hormone metabolites rather than the hormones themselves. The results tell you about downstream breakdown products, which can give a useful picture of overall androgen metabolism. But they are not directly interchangeable with serum DHT values. If your doctor has ordered a serum DHT test and you bring back a dried urine panel, those are two different types of information. Urine-based testing can complement a blood test, but for most clinical decisions, serum measurements remain the reference standard.

What Can Throw Off Your Results

Several common factors can distort DHT readings in ways that might confuse you or your doctor if nobody accounts for them.

Medications That Directly Alter DHT

If you are taking a 5-alpha reductase inhibitor like finasteride or dutasteride for hair loss or prostate symptoms, your DHT will be lower than it would otherwise be. These drugs work specifically by blocking the enzyme that converts testosterone to DHT. In one study, a single dose of finasteride reduced serum DHT by about 65 percent within 12 hours, and multiple daily doses maintained a reduction in the range of 52 to 60 percent.⁹ Dutasteride, which blocks both subtypes of the enzyme, is expected to suppress DHT even more aggressively, though one study found a reduction of only about 38.5 percent, considerably less than the roughly 90 percent reported in earlier trials.¹⁰ The takeaway is that if you are on one of these drugs, your DHT level on the lab report does not reflect your natural baseline, and the degree of suppression can vary from person to person.

Testosterone replacement therapy also shifts things, sometimes in an unexpected direction. In a group of older men with low testosterone who were given testosterone supplementation, average DHT actually declined from about 0.95 to 0.55 nmol/L. The drop was most pronounced in men whose starting DHT was in the higher part of the normal range, and the researchers attributed it to a reduction in 5-alpha reductase activity.¹¹ So if you are on testosterone therapy and your DHT comes back lower than expected, that does not necessarily indicate a problem. It may reflect the way your body adjusts enzyme activity in response to rising testosterone.

Supplements, Especially Biotin

Here is one that catches people off guard. Biotin, a B vitamin found in many hair, skin, and nail supplements, can interfere with certain lab assays. Many immunoassay-based hormone tests use the streptavidin-biotin system in their chemistry, and having excess biotin in your blood sample can throw off the readings.¹² This is particularly ironic because people taking biotin for hair loss are often the same people who end up getting their androgens checked. If you are supplementing with biotin, stop it for at least two to three days before any blood draw for hormone testing, or ask your lab whether their assay is susceptible to biotin interference.

Timing Within the Menstrual Cycle

For women, the timing of a blood draw relative to the menstrual cycle may matter less for DHT than for testosterone. Research measuring hormones across the menstrual cycle found that while total and free testosterone levels rose through the follicular phase and peaked around midcycle, DHT itself did not change significantly across the cycle.¹³ That said, if your doctor is also checking testosterone, timing the draw for the early follicular phase (days 2 through 5 of your period) remains the standard recommendation for the most consistent comparison to reference ranges.

Reading Your Results

Reference ranges for DHT vary by lab and by the assay method used, so the numbers printed on your report are the ones to pay attention to, alongside the specific reference range that lab provides. As a rough guide for men, typical adult serum DHT measured by LC-MS/MS falls somewhere in the range of 0.3 to about 1.5 nmol/L, but this varies with age and the specific lab’s validated range. Women generally have substantially lower levels. One useful detail from research comparing the sexes is that the DHT-to-testosterone ratio is roughly 1:4 in women and about 1:13 in men, meaning women convert a proportionally larger share of their circulating testosterone into DHT.¹³

The testosterone-to-DHT ratio can itself be a useful diagnostic marker. In conditions like 5-alpha reductase deficiency, testosterone will be normal or high while DHT is disproportionately low, producing an abnormally high T-to-DHT ratio. Research has found that this ratio is not simply a function of sex but rather a function of testosterone concentration. Whether testosterone is coming from the body’s own production or from external administration, higher testosterone levels tend to produce proportionally different ratios.¹⁴ This means a single DHT number without a simultaneous testosterone measurement is less informative than the two readings together.

What a Blood Test Cannot Tell You

One limitation of serum DHT measurement that is rarely discussed with patients is that blood levels do not perfectly reflect what is happening inside target tissues. DHT is produced locally within the prostate, skin, and hair follicles by 5-alpha reductase acting right at the site where the hormone is needed. Tissue concentrations of DHT can be many times higher than what circulates in the blood. A man with a “normal” serum DHT level can still have significant DHT-driven hair loss or prostate enlargement if local conversion in those tissues is elevated. This is one reason why doctors typically do not diagnose androgenic alopecia or BPH based on a DHT blood test alone. The clinical presentation, physical exam findings, and sometimes imaging or biopsy matter more than the serum number.

This also helps explain why two people with identical blood levels can have very different outcomes. The sensitivity of your hair follicles or prostate tissue to DHT depends on androgen receptor density and other local factors, not just on how much DHT is floating around in your bloodstream. Checking serum DHT gives you one piece of the puzzle, but the effects of DHT are ultimately a tissue-level story.

Direct-to-Consumer Testing and Its Limits

A growing number of companies now offer at-home hormone testing kits, where you collect a blood spot or saliva sample and mail it in. These can feel more accessible than booking a doctor’s visit, but they come with genuine drawbacks. A review of reproductive direct-to-consumer testing raised concerns about the lack of standardized laboratory methodology, the absence of strong governmental regulation over these services, and questions about the clinical validity and actionability of results.¹⁵

In practical terms, this means you could receive a DHT result from a mail-in kit and have no clear idea whether the method used was an immunoassay or mass spectrometry, whether the reference range was validated for the specific sample type (finger-prick blood spots behave differently from a full venous draw), or whether the result actually changes any medical decision. These tests are best thought of as screening tools. If a DTC result comes back flagged as abnormal, the next step should be a repeat measurement at a clinical lab, drawn from a vein, using a well-characterized assay, and interpreted by someone who can factor in your symptoms and history.

Natural Supplements That Claim to Lower DHT

Saw palmetto is probably the most widely marketed natural DHT-lowering supplement. It is an extract from the fruit of a small palm tree, and it has been studied both for hair loss and for prostate symptoms. A systematic review found that randomized trials and prospective studies generally showed positive effects of saw palmetto supplements (at doses of 100 to 320 mg) in patients with androgenic alopecia.¹⁶ Computational modeling has suggested that both the sterols and fatty acids in the extract could play a role in inhibiting 5-alpha reductase through a competitive mechanism.¹⁷

However, the head-to-head data against pharmaceutical 5-alpha reductase inhibitors is humbling. In a direct comparison study, finasteride at a standard dose reduced serum DHT by over 50 percent, while saw palmetto at a dose of 320 mg per day showed no statistically significant reduction in serum DHT over the same period.⁹ The clinical benefits that have been observed with saw palmetto may work through mechanisms other than straightforward DHT suppression in the blood, or the effect on tissue-level DHT may not be captured by serum measurements. Either way, if you take saw palmetto and then get your serum DHT tested, you should not expect the dramatic reduction you would see with finasteride or dutasteride.

When Repeat Testing Makes Sense

A single DHT measurement is a snapshot. Hormone levels fluctuate based on time of day, recent meals, stress, sleep quality, and a dozen other variables. If your first result is borderline or unexpected, repeating the test under the same conditions (same time of day, same lab, same fasting status) is standard practice before making any treatment decisions. This is especially true when the initial result was obtained by immunoassay, given how much variability those methods introduce at lower concentrations.⁶

Serial testing also becomes relevant if you are monitoring the response to a medication. If you started finasteride for hair loss, for example, checking DHT after a few months lets your provider confirm the drug is actually suppressing the target hormone. The same logic applies to dutasteride, where the expected degree of suppression has been inconsistent across studies, so verifying what is actually happening in your body has value.¹⁰ For men on testosterone replacement therapy, periodic DHT measurement helps track whether the testosterone-to-DHT conversion is behaving as expected, since that ratio can shift over time as the body adapts.¹¹

For women being evaluated for PCOS or hirsutism, repeat testing may be less about tracking a trend and more about confirming the initial finding, particularly if the first sample was drawn at an inconvenient point in the menstrual cycle or if the lab used an immunoassay without chromatographic cleanup. Getting it right the second time, with a clear methodology and proper timing, can save months of uncertainty.